function A = rowrot(A,c,s);

% This function implements the "row rotation"
% algorithm 5.1.6 in Golub and Van Loan, page 203.
% It exploits the fact that there is a 2 x 2 matrix
% which is affected by the Givens rotation, so 
% as to minimize the number of required operations.
% Notation matches Golub and Van Loan

tau1=A(1,:);
tau2=A(2,:);

A(1,:)=c'*tau1 - s*tau2;
A(2,:)=s'*tau1 + c*tau2;   % ' Transposes and conjugates
